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'OT: Re: AC Power Generation'
1998\07\25@060949 by Peter L. Peres

picon face
On Sat, 25 Jul 1998, John Fimognari wrote:

> But the power supply problem in the good old US of A interests me. I did
> not know that you guys had a such backward power distribution system.
- snip -

For them, it comes from being the first ones to get there ;) (nb: I'm not
in the USA, we have mostly the same system as you have in Australia here,
except 220 Volts per phase).

Do you have mandatory fault current breakers in the panel in every house
in Australia ? We have them here and it's a good system. Saves lives every
day I guess.

- snip -
> No wonder you guys in the USA are having problems with your PICS and
> RFI. With a floating neutral system and doddgy earthing system how do
> you get rid of the nasties in your main power supply?

You use fine products made by Corcom (line filters) and you ride the
larger common mode problems out by providing an IP2 class plastic case
that is not grounded at all ;)

> Our 240 volt, 10 amp 3 pin plugs use the same size pins,and yes we have
> the live pin burn out problem as well.

I've been thinking about this some more. I think that the burn-out happens
at insertion/extraction, by arcing, and is made much worse by operation
under high load thereafter, by heating. It would be nice if someone with
the technical capabilities would take a 4-5 year old power plug with
identical prongs that have not burned out yet, from a kettle for example,
and remove the prongs for analysis (look for oxide layer thickness
difference and/or oxygen content in the copper/tin/manganese alloy these
are usually made of) and post the results somewhere. Just to quench our
curiosity. I suppose that any semiconductor facility has the required lab
tools, they are used to examine solderability on terminals, raw material
quality and other things.

I hope that I'm not offending someone with this, but I don't like
unanswered questions of this kind.

regards,

       Peter

1998\07\25@101025 by paulb

flavicon
face
Peter L. Peres wrote:

> Do you have mandatory fault current breakers in the panel in every
> house in Australia ? We have them here and it's a good system.  Saves
> lives every day I guess.

 RCDs?  (Residual Current Detectors)  Essentially required in most
states in *domestic* situations.  Homes generally have one or two.  Of
course I put in three, with two sub-breakers on each (actually, three on
one).  Regretted it since; computers tend to go down with the ship when
another circuit faults.

 Have since obtained a couple more RDCs so when fitted I really should
have *exclusive* circuits for computers on two channels; total five
RCDs.  Made quite sure at least that the laundry circuit wasn't sharing
with anything important but the dishwasher blew a(n RCD) breaker last
night.

 Probably one of its load of hundreds of cockys got in the works.  It's
working fine right now, but it is going to be put on an off-peak
exclusive circuit sooner or later (which *won't* have an RCD) to save
money.  I jury-rigged it to finish its cycle last night by plugging into
the fridge outlet (via an extension across the kitchen floor - this
happens to lie next to the fridge semi-permanently so I can operate the
appliance tester without aggrievating the RCDs!

--
 Cheers,
       Paul B.

1998\07\25@113949 by John Fimognari

picon face
On Sat, 25 Jul 1998, John Fimognari wrote:

> But the power supply problem in the good old US of A interests me. I did
> not know that you guys had a such backward power distribution system.
- snip -

For them, it comes from being the first ones to get there ;) (nb: I'm
not
in the USA, we have mostly the same system as you have in Australia
here,
except 220 Volts per phase).

Do you have mandatory fault current breakers in the panel in every house
in Australia ? We have them here and it's a good system. Saves lives
every
day I guess.

It is now mandatory to fit 20ma tripping RCD's in all premises. The
Regulatory Authority is trying an encourage the older premises to
install them. The house supply is usually between 70amp to 90 amp single
phase, or 35 amps 3 phase. 3 phase power potential is not permitted on
the power or lighting circuits. It is only used for hot water systems,
Stoves or pumps. The RCD unit is fitted between the main switch and
power circuits. We also have power points with the RCD built into them.
They are installed as the first power point, all the others in the
circuit are then RCD protected. We had a few backyard weekend
electricians fry themselves, and a few house fires a few years ago. The
insurance companies hit the panic button and put the screws on the
pollies. In Aus it is illegal to carry out electrical work unless you
are a licenced electrician. Which I am. Unfortunately it is not illegal
to sell electrical wire and accessories in the retail industry. Hence
the backyarders frying themselves or burning their houses down. The
fines for electrical work can be anything up to $10,000AUS.

- snip -
> No wonder you guys in the USA are having problems with your PICS and
> RFI. With a floating neutral system and doddgy earthing system how do
> you get rid of the nasties in your main power supply?

I am sorry but I could not help having a dig at the USA. I have been
reading about the crazy system used in parts of the USA on the PIC list.
I would be interested in their earthing methods.

You use fine products made by Corcom (line filters) and you ride the
larger common mode problems out by providing an IP2 class plastic case
that is not grounded at all ;)

If a component has an earth attachment like the Corcom filters, an earth
wire is a mandatory connection. The problem lies with electronics
technicians who do not know the Aus Standards. We also recognise IEEE.
Aus usually follows the European Electrical Standards. The new Aus
standards are virtually are copy of the Euro standards with upgraded
insulation and larger copper sizes. The cable and accessories have to
function up to 55deg C heat. Unfortunately Aus is also a dumping ground
for anyone trying to sell their electrical products. Lucky for us the
Regulatory guys are sharp.

> Our 240 volt, 10 amp 3 pin plugs use the same size pins,and yes we have
> the live pin burn out problem as well.

I've been thinking about this some more. I think that the burn-out
happens
at insertion/extraction, by arcing, and is made much worse by operation
under high load thereafter, by heating. It would be nice if someone with
the technical capabilities would take a 4-5 year old power plug with
identical prongs that have not burned out yet, from a kettle for
example,
and remove the prongs for analysis (look for oxide layer thickness
difference and/or oxygen content in the copper/tin/manganese alloy these
are usually made of) and post the results somewhere. Just to quench our
curiosity. I suppose that any semiconductor facility has the required
lab
tools, they are used to examine solderability on terminals, raw material
quality and other things.

I hope that I'm not offending someone with this, but I don't like
unanswered questions of this kind.

regards,

       Peter

Peter,
The burnout in the plugs is caused because the socket spring contacts
are the weakest point in the connection. A 10 amp plug with 10 amps
continuously flowing through it creates heat. This travels up the plug
causing a burnout. It only happens on the live side because there is no
voltage potential in the neutral side. You will also notice AC corrosion
is only on the live side for the same reason.
I am probably boring everyone. But it remains that if you can solve the
noise and nasties on your mains supply at the source, then the
electronic equipment will function without intermittent glitches. It is
better to catch it at the source than spent time and money on fancy
filters which will probably be ineffective. This information may be
valuable for the guys who are in industrial control or electrical
/electronics interfacing. A lot good quality electronic equipment has
fried because of a dirty mains supply.
Regards,
John Fimognari

1998\07\25@144657 by Peter L. Peres

picon face
On Sat, 25 Jul 1998, John Fimognari wrote:

> On Sat, 25 Jul 1998, John Fimognari wrote:
>
> Do you have mandatory fault current breakers in the panel in every house
> in Australia ? We have them here and it's a good system. Saves lives
> every day I guess.
>
> It is now mandatory to fit 20ma tripping RCD's in all premises. The
> Regulatory Authority is trying an encourage the older premises to
- snip -
> are a licenced electrician. Which I am. Unfortunately it is not illegal
> to sell electrical wire and accessories in the retail industry. Hence
> the backyarders frying themselves or burning their houses down. The
> fines for electrical work can be anything up to $10,000AUS.

Hmm. I think in the US they have to prove that you did something wrong or
caused damage to have them come after you. Am I right ?

> - snip -
> If a component has an earth attachment like the Corcom filters, an earth
> wire is a mandatory connection. The problem lies with electronics

Not really. There are such filters made for IP2 internal shielded cases.
No ground connection required. The filter shorts the noise to the case
which is metal but enclosed inside a plastic box such that no part of it
can be touched. This works, and it's a life-saver for some projects that
have to pass tests for which they were not designed/audited. It may not be
legal everywhere though.

> standards are virtually are copy of the Euro standards with upgraded
> insulation and larger copper sizes. The cable and accessories have to
> function up to 55deg C heat. Unfortunately Aus is also a dumping ground
> for anyone trying to sell their electrical products. Lucky for us the
> Regulatory guys are sharp.

I thought equipment must be rated 55 deg. C everywhere, except industrial
which is 0-70 or 0-80 deg. C.

I wrote this:
> I've been thinking about this some more. I think that the burn-out
> happens at insertion/extraction, by arcing, and is made much worse by
- snip -
> I hope that I'm not offending someone with this, but I don't like
> unanswered questions of this kind.
>

John wrote:

- snip -
causing a burnout. It only happens on the live side because there is no
voltage potential in the neutral side.

Why would there be no potential ? If a plug with a load connected is
inserted, and the live plug touches first, then the arcing will be on the
neutral.

I've been thinking even more, and I have a new hypothesis: Most people are
right-handed, and insert plugs with the right hand. When they do this,
they push it in with the thumb more than anything else. This causes the
left prong (w. plug facing away) to touch first. The left prong is the
neutral with on our plugs, so the live touches last, and arcs more often
than not.  Does this sound better than oxyde contents ;) ?

(If you don't believe this, take a polarized plug, like an Aussie, ours or
a Schuko with installed 3rd prong), and, provided you are right-handed,
insert it into the outlet. Observe what goes in first and what pushes it
in (I assume that the cable hangs downwards and the receptacle is
vertical - the most often encountered position).

Peter

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